Making Self-watering containers
Directions for making and using self-watering
(watering from the bottom) pots
Why make and use self-watering pots?
1. They save water because all the water that is put into the (bottom) pot is used by the plant.
2. They are portable and can be moved quickly if necessary. (Do all lifting by the bottom bucket so that the contact between the wick and the soil stays intact.)
3. They are ‘home-made’ which makes them less expensive and often more durable than what is available commercially.
4. They are perfect for teaching children to garden.
Use plants that are labeled for container culture.
Many of the seed companies (Renee’s Seeds, Landreth, Scheepers Seeds, Pine Tree Seeds and more) are developing and promoting vegetables that are suited to container culture. The locally owned greenhouses are offering a growing number of these vegetables – tomatoes, peppers, chard, zucchini, bush beans, cucumbers that do well in self-watering pots. If you are looking for plants for container culture, be obvious about your requests. If you get dumb answers, go somewhere else.
Understanding the purpose of the wick.
The wick is the provider of water to the soil and plant roots in the top bucket through an osmatic process. The water in the bottom reservoir is drawn into the soil through the wick and the process of osmosis moves the water into the soil in the top bucket. The osmatic process slows or stops when the soil medium (in the top bucket) is uniformly moist. A growing plant is constantly using water and this action of water uptake by the roots keeps the osmatic condition continuously working. It is ‘Nature’s automatic pump.’ However, if the soil in the wick is ever separated from its contact with the soil in the upper bucket, the osmatic process will stop causing loss of water to the plant roots.
Constructing the wick.
The wick can be made from anything round – pvc pipe, pvc drain pipe, a tin can, etc. A square piece (as in a downspout) works as well. Wicks made of metal (cans) can be difficult to work with and their ‘burrs’ where the holes were made can be problematical. If you are working with a 5-gallon bucket system, a wick larger than 4” in diameter might just take up too much space.
Drill 8-12 ¼” – 3/8” holes in the body of the wick (so water can enter). Do not use larger bits because soil can flush out of larger holes. The purpose of the holes in the wick is to allow water IN and not to allow soil to wash OUT.
How to cut the space for the wick to enter into the top bucket.
There are a variety of cutting tools – a rotozip which is effective but can be hard to handle. A safer way is as follows: drill ¼” or 3/8” holes around the circle you have traced on the outside center bottom of the top bucket. (This marks the area where the wick will enter slightly into the top bucket.) Leave a very small space between the holes. Remove this material between the holes with a sharp knife and check to be certain that the wick enters the top bucket smoothly with a good fit.
How to find the place for the hole to add water (to the bottom bucket).
Place the two identical buckets together, one inside the other. Place a bright, lighted flashlight inside the top bucket, which will expose the line where the top bucket ends. Make a small mark on the outer bucket at that point. Then, using that line as the top of a circle or oval, make a mark sufficient for a hose or the nozzle of a watering wand to enter. When the hole is made you should be able to see or feel with your finger the bottom of the top bucket. (This cutting the water hole is possible but less easy with black buckets.)
Some important reminders:
1. Know what your buckets contained before you decided to repurpose them. Avoid containers that held toxic solutions. It is probably better either to buy new buckets, get them from bakeries and groceries or use the containers of pet food and cat sand.
2. Know that you will be putting your plants in a special growing mix and will not be using garden soil. Our personal experience is that using equal portions of Ball potting mix (no water crystals, no fertilizer pellets), city yardwaste compost and our home-made manure and garden waste compost plus a handful or two of either vermiculite or perlite is fine. The soil needs to be light.
3. You will need to fertilize on a regular basis. Use water-soluble fertilizers and simply add them to the water reservoir. Strength and frequency of fertilizer use depends, of course, on the needs of the plants.
How important is ‘pretty’?
The purpose of this system is to use water wisely and appropriately for the plant. Also, we are ‘repurposing’ the containers. We are also promoting this system because it is appropriate for small yards/terraces/porches. The buckets will look like buckets and unless you want to spend time and money to change that – you will have ordinary buckets of extraordinary plants that will flourish and provide you nice vegetables.
The Internet is full of information about this system. Read carefully and critically. While some can be helpful and suggest new ideas, not all of it is worthwhile or correct.